circulatory system

1. Essentials of Human Anatomy & Physiology
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Seventh Edition
Elaine N. Marieb
Chapter 11
The Cardiovascular
System

2. Objectives
After this lesson you should have understand the following:
• Functions of heart
• Covering of the heart
• Anatomy
• Types of chambers
• Blood circualation
• Types of valves
• Cardiac cycle
• Heart circulation
• Regualation of heart beat
• Diffusion
• Pulse and blood pressures

3. Development of the heart

4. The Cardiovascular System
Slide 11.1
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∙ A closed system of the heart and blood
vessels
▪ The heart pumps blood
▪ Blood vessels allow blood to circulate to all
parts of the body
∙ The function of the cardiovascular
system
▪ To deliver oxygen and nutrients and to
remove carbon dioxide and other
waste products

5. The Heart
Slide
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∙ Location
∙Thorax between the lungs
∙Pointed apex directed toward left hip
∙The average gross weight of the heart
∙31-40 years,
✔ 289.6 g (men) & 284.7 g (women)
▪ 61-70 years,
✔ 345.9 g (men) & 285.1 g (women)

6. • Dextrocardia
– Rare heart condition in which your heart points
toward the right side of your chest instead of
the left side

7. The Heart
Slide
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Figure 11.1

8. The Heart: Coverings
Slide 11.3
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∙ Pericardium – a double serous
membrane
∙Visceral pericardium
∙Next to heart
∙Parietal pericardium
∙Outside layer
∙ Serous fluid fills the space between the
layers of pericardium

10. The Heart: Heart Wall
Slide 11.4
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∙ Three layers
∙Epicardium
∙Outside layer
∙This layer is the parietal pericardium
∙Connective tissue layer
∙Myocardium
∙Middle layer
∙Mostly cardiac muscle
∙Endocardium
∙Inner layer
∙Endothelium

11. External Heart Anatomy
Slide 11.5
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12. The Heart: Chambers
Slide 11.6
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∙ Right and left side act as separate pumps
∙ Four chambers
∙Atria
∙Receiving chambers
∙Right atrium
∙Left atrium
∙Ventricles
∙Discharging chambers
∙Right ventricle
∙Left ventricle

15. Blood Circulation
Slide 11.7
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Figure 11.3

16. The Heart: Valves
Slide 11.8
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∙ Allow blood to flow in only one direction
∙ Four valves
∙Atrioventricular valves – between atria and
ventricles
∙Bicuspid valve (left)
∙Tricuspid valve (right)
∙Semilunar valves between ventricle and
artery
∙Pulmonary semilunar valve
∙Aortic semilunar valve

17. The Heart: Valves
Slide 11.9
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∙ Valves open as blood is pumped
through
∙ Held in place by chordae tendineae
(“heart strings”)
∙ Close to prevent backflow

18. Operation of Heart Valves
Slide
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Figure 11.4

19. Valve Pathology
• Incompetent valve = backflow and repump
• Stenosis = stiff= heart workload increased
• May be replaced
• Lup Dub Heart Sound

20. The Heart: Associated Great
Vessels
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∙ Aorta
∙Leaves left ventricle
∙ Pulmonary arteries
∙Leave right ventricle
∙ Vena cava
∙Enters right atrium
∙ Pulmonary veins (four)
∙Enter left atrium

22. Coronary Circulation
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∙ Blood in the heart chambers does not
nourish the myocardium
∙ The heart has its own nourishing
circulatory system
∙Coronary arteries
∙Cardiac veins
∙Blood empties into the right atrium via the
coronary sinus

25. Cardiac Pathology
• Rapid heart beat
• = Inadequate blood
• = Angina Pectoris

26. The Heart: Conduction System
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∙ Intrinsic conduction system
(nodal system)
∙Heart muscle cells contract, without nerve
impulses, in a regular, continuous way

27. The Heart: Conduction System
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∙Special tissue sets the pace
∙Sinoatrial node (right atrium)
∙Pacemaker
∙Atrioventricular node (junction of r&l atria
and ventricles)
∙Atrioventricular bundle (Bundle of His)
∙Bundle branches (right and left)
∙Purkinje fibers

28. Heart Contractions
Slide
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Figure 11.5

29. • Heart's sinus node
▪ Natural pacemaker (found in the upper
right chamber of the heart, known as the
atrium). It sends an electrical impulse to
make your heart beat

35. • Three formations
– P wave: impulse across atria
– QRS complex: spread of impulse down septum,
around ventricles in Purkinje fibers
– T wave: end of electrical activity in ventricles
Electrocardiograms (EKG/ECG)

38. Electrocardiograms (EKG/ECG)
(cont.)
Figure 8.15B, C

41. A P wave on an electrocardiogram represents a phase of electrical
activity that causes the atria of the heart to contract.
on the
electrocardiogram
of a healthy
individual.
The P wave is the first wave found

42. • A healthy P wave is initiated in the sinoatrial
node of the right atrium.
• Action potentials generated at this node spread
throughout the atria.
• This means that the right atrium contracts
slightly earlier than the left atrium.

43. • The heart conduction pathway in the atria is
composed of the sinoatrial node,
– Thorel’s bundle
• Conducts action potentials from the SA node along
the back of the right atrium
– Wenckebach’s bundle
• Through the right side and front of the right atrium.
– Bachmann’s bundle
• Is an extension of a group of fibers that cross far
into the muscle of the left atrium.
– The atrioventricular node.

44. Pathology of the Heart
• Damage to AV node = release of ventricles
from control = slower heart beat
• Slower heart beat can lead to fibrillation
• Fibrillation = lack of blood flow to the heart
• Tachycardia = more than 100 beats/min
• Bradychardia = less than 60 beats/min

45. • Heart conduction and contraction does not
need the brain to function.
• The medulla oblongata of the brainstem
controls how quickly or slowly heart
muscle contracts

46. • Pacemaker cells should only be found at the
sinoatrial node (SAN) and atrioventricular
node (AVN).
• These cells are the captains of the cardiac
pacemaker.
• Regular (healthy) heart muscle cells do not
display automaticity;
• Ions involved in heart muscle contraction
(sodium, potassium, and calcium) are
imbalanced, regular cardiomyocytes may
also start to generate action potentials.

47. • P wave: depolarization of the atria. As
gravity helps blood to flow into the
ventricles, less muscle contraction is
required here. This is why the P wave is
smaller than the R and T waves.
• PR interval: a short pause before the QRS
complex

48. • Q wave: depolarization of the top of the
ventricular septum by the bundle of His. A
small, downward-pointing wave.
• R wave: ventricular depolarization at the
thickest part of the ventricular walls via the
bundle branches – this is why the R wave is
the biggest (more voltage is needed).

49. • S wave: depolarization in the Purkinje
fibers. Opposite curve direction to R wave
as signals travel from the bottom of the
ventricles and move upwards.
• ST-segment: time required for each
ventricle to completely depolarize (relax)
• T wave: complete repolarization
(relaxation) of the ventricles.

50. The Heart: Cardiac Cycle
Slide
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∙ Atria contract simultaneously
∙ Atria relax, then ventricles contract
∙ Systole = contraction
∙ Diastole = relaxation

51. Filling of Heart Chambers –
the Cardiac Cycle
Slide
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Figure 11.6

52. The Heart: Cardiac Output
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∙ Cardiac output (CO)
∙Amount of blood pumped by each side of
the heart in one minute
∙CO = (heart rate [HR]) x (stroke volume
[SV])
∙ Stroke volume
∙Volume of blood pumped by each ventricle
in one contraction

53. Cardiac output, cont.
• CO = HR x SV
• 5250 ml/min = 75 beats/min x 70 mls/beat
• Norm = 5000 ml/min
• Entire blood supply passes through body
once per minute.
• CO varies with demands of the body.

54. Cardiac Output Regulation
Slide
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Figure 11.7

55. The Heart: Regulation of Heart
Rate
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∙ Stroke volume usually remains relatively
constant
∙Starling’s law of the heart – the more that
the cardiac muscle is stretched, the
stronger the contraction
∙ Changing heart rate is the most
common way to change cardiac output

56. Regulation of Heart Rate
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∙ Increased heart rate
∙Sympathetic nervous system
∙Crisis
∙Low blood pressure
∙Hormones
∙Epinephrine
∙Thyroxine
∙Exercise
∙Decreased blood volume

57. The Heart: Regulation of Heart
Rate
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∙ Decreased heart rate
∙Parasympathetic nervous system
∙High blood pressure or blood volume
∙Dereased venous return
∙In Congestive Heart Failure the heart is
worn out and pumps weakly. Digitalis
works to provide a slow, steady, but
stronger beat.

58. Congestive Heart Failure (CHF)
• Decline in pumping efficiency of heart
• Inadequate circulation
• Progressive, also coronary atherosclerosis, high
blood pressure and history of multiple Myocardial
Infarctions
• Left side fails = pulmonary congestion and
suffocation
• Right side fails = peripheral congestion and edema

59. Blood Vessels: The Vascular
System
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∙ Taking blood to the tissues and back
∙Arteries
∙Arterioles
∙Capillaries
∙Venules
∙Veins

60. The Vascular System
Slide
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Figure 11.8b

61. Blood Vessels: Anatomy
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∙ Three layers (tunics)
∙Tunic intima
∙Endothelium
∙Tunic media
∙Smooth muscle
∙Controlled by sympathetic nervous
system
∙Tunic externa
∙Mostly fibrous connective tissue

62. Differences Between Blood Vessel
Types
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∙ Walls of arteries are the thickest
∙ Lumens of veins are larger
∙ Skeletal muscle “milks” blood in veins
toward the heart
∙ Walls of capillaries are only one cell
layer thick to allow for exchanges
between blood and tissue

63. Movement of Blood Through
Vessels
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∙ Most arterial blood is
pumped by the heart
∙ Veins use the milking
action of muscles to
help move blood
Figure 11.9

64. Capillary Beds
Slide
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∙ Capillary beds
consist of two
types of vessels
∙Vascular shunt –
directly connects an
arteriole to a venule
Figure 11.10

65. Capillary Beds
Slide
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∙True capillaries –
exchange vessels
∙Oxygen and
nutrients cross to
cells
∙Carbon dioxide
and metabolic
waste products
cross into blood
Figure 11.10

66. Diffusion at Capillary Beds
Slide
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Figure 11.20

67. Vital Signs
• Arterial pulse
• Blood pressure
• Repiratory Rate
• Body Temperature
• All indicate the efficiency of the system

68. Pulse
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∙ Pulse –
pressure wave
of blood
∙ Monitored at
“pressure
points” where
pulse is easily
palpated
Figure 11.16

69. Blood Pressure
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∙ Measurements by health professionals
are made on the pressure in large
arteries
∙Systolic – pressure at the peak of
ventricular contraction
∙Diastolic – pressure when ventricles relax
∙ Pressure in blood vessels decreases as
the distance away from the heart
increases

70. Measuring Arterial Blood Pressure
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Figure 11.18

71. Blood Pressure: Effects of Factors
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∙ Neural factors
∙Autonomic nervous system adjustments
(sympathetic division)
∙ Renal factors
∙Regulation by altering blood volume
∙Renin – hormonal control

72. Blood Pressure: Effects of Factors
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∙ Temperature
∙Heat has a vasodilation effect
∙Cold has a vasoconstricting effect
∙ Chemicals
∙Various substances can cause increases or
decreases
∙ Diet

73. Variations in Blood Pressure
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∙ Human normal range is variable
∙Normal
∙140–110 mm Hg systolic
∙80–75 mm Hg diastolic
∙Hypotension
∙Low systolic (below 110 mm HG)
∙Often associated with illness
∙Hypertension
∙High systolic (above 140 mm HG)
∙Can be dangerous if it is chronic